Bioactive agents released from a medical device can be used to treat or mitigate a variety of conditions. An angioplasty balloon, for example, may be configured to release one or more antiproliferative agents, such as paclitaxel, in order to prevent or reduce the incidence of restenonsis. Restenosis refers to the renarrowing of the vascular lumen following vascular intervention. In another example, a prosthetic valve may be configured to deliver an antithrombotic agent, such as heparin, in order to inhibit thrombus formation at the site of implantation. Other combinations of medical devices and bioactive agents may be used to treat a variety of other conditions.
These drug eluting devices are typically configured to deliver the bioactive agent directly to an exposed, exterior surface of the therapeutic target. A paclitaxel coated angioplasty balloon, for example, may be delivered to a site of vascular treatment and thereafter inflated so that the exterior of the balloon contacts the vessel wall. The paclitaxel may then diffuse into the vessel wall from the balloon exterior surface. In some instances, however, delivery of a therapeutically effective amount of bioactive agent can be hindered by the movement of body fluid through or past the implanted device. Specifically, body fluid can wash away or dilute the bioactive agent, preventing effective delivery.
What is needed are devices and methods for facilitating effective delivery of one or more bioactive agents to selected therapeutic targets. In particular, devices are needed that can facilitate drug uptake and diffusion into the therapeutic target.